// SHA1
function add(x, y) {
    return((x & 0x7FFFFFFF) + (y & 0x7FFFFFFF)) ^ (x & 0x80000000) ^ (y & 0x80000000);
}

function SHA1hex(num) {
    var sHEXChars = "0123456789abcdef";
    var str = "";
    for(var j = 7; j >= 0; j--)
        str += sHEXChars.charAt((num >> (j * 4)) & 0x0F);
    return str;
}

function AlignSHA1(sIn) {
    var nblk = ((sIn.length + 8) >> 6) + 1,
        blks = new Array(nblk * 16);
    for(var i = 0; i < nblk * 16; i++) blks[i] = 0;
    for(i = 0; i < sIn.length; i++)
        blks[i >> 2] |= sIn.charCodeAt(i) << (24 - (i & 3) * 8);
    blks[i >> 2] |= 0x80 << (24 - (i & 3) * 8);
    blks[nblk * 16 - 1] = sIn.length * 8;
    return blks;
}

function rol(num, cnt) {
    return(num << cnt) | (num >>> (32 - cnt));
}

function ft(t, b, c, d) {
    if(t < 20) return(b & c) | ((~b) & d);
    if(t < 40) return b ^ c ^ d;
    if(t < 60) return(b & c) | (b & d) | (c & d);
    return b ^ c ^ d;
}

function kt(t) {
    return(t < 20) ? 1518500249 : (t < 40) ? 1859775393 :
        (t < 60) ? -1894007588 : -899497514;
}

function sha1(sIn) {
    var x = AlignSHA1(sIn);
    var w = new Array(80);
    var a = 1732584193;
    var b = -271733879;
    var c = -1732584194;
    var d = 271733878;
    var e = -1009589776;
    for(var i = 0; i < x.length; i += 16) {
        var olda = a;
        var oldb = b;
        var oldc = c;
        var oldd = d;
        var olde = e;
        for(var j = 0; j < 80; j++) {
            if(j < 16) w[j] = x[i + j];
            else w[j] = rol(w[j - 3] ^ w[j - 8] ^ w[j - 14] ^ w[j - 16], 1);
            var t = add(add(rol(a, 5), ft(j, b, c, d)), add(add(e, w[j]), kt(j)));
            e = d;
            d = c;
            c = rol(b, 30);
            b = a;
            a = t;
        }
        a = add(a, olda);
        b = add(b, oldb);
        c = add(c, oldc);
        d = add(d, oldd);
        e = add(e, olde);
    }
    let SHA1Value = SHA1hex(a) + SHA1hex(b) + SHA1hex(c) + SHA1hex(d) + SHA1hex(e);
    return SHA1Value.toLowerCase();
}

export default sha1;
